Abstract
Atmospheric vortices have been classified either according to their horizontal dimensions or to their maximum windspeed. For the purpose of reclassifying them, taking both horizontal dimensions and maximum windspeed simultaneously into consideration, these vortices were located on a maximum windspeed versus diameter diagram (Fig.1).
When the s u btropical mesocyclone of 1 September 1960, which formed over tropical waters and hit Japan the next day (Fig.2), was placed on this diagram, it was found that the storm in question was located on the border line between the tropical depressions and the mesocyclones.
The mesocyclone was accompanied by arc-shaped echoes around the center and by a curved echo band in the eastern sector far from the center (Fig.3). The area of composite mesohighs was accompanied by an echo band (Fig.9). The pressure field of the storm was characterized by a funnel-shaped profile superimposed by an excess-pressure field of the marked mesohigh with a pressure-jump line along its progressive side (Figs.6 and 7). Due to the fact that most of the squall-line activities took place in eastern sectors of the storm and that the cloud mass encircling the storm center did not grow to the cirrus level, it was characterized by a strictly asymmetric structure (Figs.8 and 11).
A three-dimensional analysis of the wind field was made by making use of the existing techniques of time-to-space conversions and interpolation for the construction of vertical space cross-section. and constant level charts. Results showed that the subtropical mesocyclone was characterized by an overall mass inflow which was about five times larger than that of a large thunderstorm, while it was only about one fifth that of a mature hurricane such as Herricane Daisy of 1958 (Fig.14).
